A Consistency check is a process performed by Data Protection Manager to check and correct any inconsistencies between the protected data and its replica.
Consistency checks can be scheduled to occur automatically or be performed manually within the DPM console, however, you can also kick-off a consistency check using PowerShell.
Start-DatasourceConsistencyCheck -datasource <datasource>
This will start a standard consistency check, just the same as if you were to click the Perform consistency check . . . action in the DPM Administrator console. Utilizing PowerShell though you can start a heavy weight validation consistency check using the -Heavyweight parameter.
Start-DatasourceConsistencyCheck -datasource <datasource> -HeavyWeight
Starting a heavy weight consistency check process checksums the contents of each file being protected. This is a much deeper level of consistency check that checks the integrity of the protected data by re-computing the checksum and comparing it against the stored one. DPM will then repair any inconsistencies between the checksums to guarantee that the stored replica is complete and consistent. Bear in mind though that a heavy weight consistency check is a much bigger job than a standard consistency check so is likely to consume more DPM server resources and transfer more data over the network.
I was going to write a script on how to use the Start-DatasourceConsistencyCheck cmdlet in a PowerShell script but I found that there is already a great script on the Microsoft Ctrl-P blog on invoking a consistency check.
http://blogs.technet.com/dpm/archive/2008/04/10/dpm-powershell-script-invoking-a-consistency-check.aspx
Any comments or questions, please feel free to register and post :-)
David